The future of off-highway drivelines

2017-05-16
Shelley Knust

When you think of Cummins and its 100-year history, you think of its expertise in diesel engine technology. This tradition continues with its latest Stage V engines, which will continue to develop and be lighter, more powerful and more efficient, said Shelley Knust, Executive Director - Off-Highway Engineering at Cummins. But the company is not solely focused on diesels.

“Approaching our second century, we see alternative power as a complement to diesel. We call it energy diversity, providing a range of powertrain solutions for customers: clean diesel, renewables, natural gas, gasoline, hybrids and electric power. Our integration expertise, built up over many years, enables us to help manufacturers define the most appropriate solution for their equipment, whatever the power source,” she said.

Cummins understands that off-highway equipment manufacturers are continuing to push for more efficient, clean and capable powertrains, with an expectation to do more with less, and improved performance and transient response while reducing fuel consumption, tailpipe (including CO2) and noise emissions, especially in urban areas.

“Powertrain and vehicle electrification can meet those needs in a variety of ways. However, the varying loads and duty cycles of off-highway equipment means it is not one-size-fits-all. Cummins is investigating a range of concepts such as alternate fuels, parallel hybrids, range extenders/plug-in hybrids and full electric to provide customers with the best solution for their machines. We will leverage both on- and off-highway markets to do that cost-effectively,” said Knust.

Parallel hybrids can deliver efficiency improvements for large forklift trucks. An 8- to 16-ton truck using a 100-kW diesel plus a 10- to 25-kW motor generator is showing major fuel consumption improvements, up to 28%. That is achieved through a range of options, such as stop-start, reducing fuel use, engine operating hours and emissions; running accessories such as the fan on electric power, reducing parasitic loss; and energy recovery from the driveline and hydraulic system. Integrating the electric motor means that the driveline delivers better transient response while the engine runs at more optimum operating points.

A plug-in hybrid is suitable for applications such as mobile cranes, using diesel for transport and plug-in for crane operation. That allows silent working with reduced tailpipe emissions on urban construction sites. Fuel consumption is reduced by up to 50% on the overall duty cycle.

A full-electric driveline, being trialed in a delivery van, will offer a solution for a range of off-highway equipment, such as drills, underground mine trucks and terminal tractors. Using a direct DC drive with 200-kW peak propulsion/regen, it has a 62 kW·h NMC (nickel manganese cobalt) lithium-ion battery pack with a 4-hour charge time. The pilot is providing operating experience and demonstrating that the system is modular and expandable, depending on power needs.

Construction sites that do not have easy access to electricity, and operate a number of Cummins-powered plug-ins and electric vehicles, can be supported with Cummins low-emissions electrical power generation products, enabling a turnkey solution from one supplier.

"Connectivity and data management will play an increasingly important role in unlocking potential from this diverse range of future off-highway drivelines," said Knust. "This technology is emerging from basic data-gathering into complex systems that optimize asset management and drive efficiency. Operators will be able to realize further savings through even deeper understanding of their business."

One example is over-the-air (OTA) programming, enabling remote updates of calibrations. On-demand optimization of the engine system tailored to the site it is working on will achieve the best balance of productivity and efficiency. A wheeled excavator can use OTA technology to enable calibration updates and optimize system performance based on how it is being used, either driving on the road between worksites or working on site.